Ventilation – Mine – With partition means
Reexamination Certificate
2000-03-30
2002-07-30
Neuder, William (Department: 3672)
Ventilation
Mine
With partition means
C049S118000, C049S368000, C405S144000
Reexamination Certificate
active
06425820
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a mine door operating system usable with two or more mine doors such as in an airlock arrangement.
Doors used in mines operate under conditions not usually encountered by typical doors. Mine doors have door leafs that tend to be heavy and dimensionally large and are thus subject to large forces due at least in part to air flow in the mine and consequent air pressure differentials on opposite sides of a door. A leaf can be as large as 10 feet wide and 20 feet high and sometimes even larger and weigh more than a thousand pounds when designed for pressure differentials of seven inches of water gauge and over two thousand pounds for a pressure differential of 20 inches of water gauge. The leafs can thus be subject to large forces from the air pressure differential on opposite sides of the leafs. Even a small pressure differential can create large forces on the large leafs making it difficult to control their movement during opening and closing and difficult to start opening movement and complete closing. Further, leafs need to be positively driven particularly in the closing direction to prevent door runaway and impact when the leafs reach the end of their closing movement, particularly when the closing movement is toward the low pressure end of the mine, the normal condition. Continued impact and runaway would cause damage and premature wear to the leaf drive, leaf and door frame.
Additionally, to reduce the risk of damage and to improve safety, it would be desirable to simply and reliably lock the leafs in both the open and closed positions and at any position in-between should there be a power outage or in the event the leaf encounters an obstruction during movement. It would also be desirable to be able to manually override the locked condition of any leaf.
Air locks are provided in mines to allow vehicles and personnel to pass thru mine passageways while controlling air flow between passageways or through a passageway and/or for fire prevention and control. Air locks use at least two doors of the above described type, a mine side or return air side door and a mine entrance or fresh air side door. In some mines, e.g., coal mines, air locks are mandatory under government regulations. In an air lock, at least two doors are spaced apart along a mine passageway with one door being located at the mine end of the air lock and the other door being located at the entrance side (in some cases this side is referred to as the fresh air side and is upstream relative to normal air flow) of the air lock.
FIG. 11
illustrates, in simplified form, a coal mine. The mine includes an air intake passageway (AIP) with an air inlet opening (AI) connected to a mine face passageway (MFP) to provide fresh air to the mine face. In normal operation, fresh air flows to the mine face thru the intake passageway. An air outlet opening (AO) is connected to the mine face via a air exit passageway (AEP). Air flowing across the mine face from the air intake is discharged through the air outlet. A neutral passageway (NP) connects the mine face to the exterior of the mine and is commonly in parallel to the air intake passageway and the air exit passageway. The neutral passageway provides for normal passage of personnel, machinery and mined material between the mine face and the mine exterior. In some locations in a mine, e.g., the air intake passageway AIP the doors of an airlock, AL, will all be considered to be fresh air (designated FA) side doors even though one of the doors is more adjacent the mine face than another door. All doors of an airlock AL may also be considered to be return air (RA) side doors even though one door is more adjacent the exit than another door, e.g., in an air exit passageway AEP, as defined by regulatory authorities. The neutral passageway has an airlock AL. The airlock in a neutral passageway is considered to have all doors in fresh air. Airflow, for normal operation is from the entrance, high pressure side of the mine, the air intake to the air outlet, the low pressure side of the mine. The pressure differential and flow rate in a neutral passageway are low relative to those in air intake passageways and air outlet passageways. In normal operation, one door of an air lock remains closed while the other door is open to allow movement into or out of the air lock while preventing air flow therethrough. Air lock doors need to be power operated for personnel convenience and to also manage movement of large leafs and the forces applied to the leafs due to the aforementioned pressure differentials. Since the normal air flow in a mine may reverse, the doors and leaf drives are preferably able to accommodate the reversal of force direction on the leafs and still properly operate. Also, the leafs are preferably positively held in the open and closed positions and in any position in-between where the leafs may be stopped.
Current leaf drive systems typically use a separate leaf drive for each door with each door utilizing a separate power source. The use of multiple power sources has been found to be desirable because the hydraulic piping is short which provides quicker response of the leaf drive and less play or give in the drive system. Such a system also utilizes two separate control systems each operating a respective door and requiring a separate housing for the power source and its control system. Further, when the doors are interlocked, the control system utilizes the interlock switches of one door to provide a signal that it is or is not permissible to open the leafs of the other door. The control systems are not interconnected providing an opportunity for the leafs of the multiple doors to malfunction since the controllers are not interconnected.
Leaf drive systems like those used with air locks, even though generally effective, do have drawbacks. They use power sources at separate locations, e.g., hydraulic pumps, each with their own control system also at separate locations. The separate control systems would need to be interfaced to effect proper and safe operation particularly with regard to interlocking so that one door cannot be opened unless the other door is closed. Another problem is having control circuit components on the mine side of the fresh air side door, i.e. in return air. When the second door is in return air, the air lock chamber is part of the return air side of the air lock and in some mine environments, like coal mines, will have to have sealed (explosion proof) components to eliminate ignition sources. Explosion proof as used herein means that a device such as a motor or component housing will not let ignited combustion products out of the device. Mine regulations as promulgated by MSHA (Mining Safety and Health Administration) refer to such equipment as “permissible” and regulate what will meet the standards of permissible. MSHA designates what equipment is permissible in particular environments. What is permissible or explosion proof will vary by the environment in which the equipment will be used. For example, what is permissible in a lead mine will not necessarily by permissible in a coal mine where methane may be present. If a combustible gas like acetylene is potentially present, equipment that is permissible for a methane environment may not be permissible in the acetylene environment. For environments where combustibles may be present, e.g., methane, meeting the requirements of “permissible” increases the cost of enclosures for control circuit components. Any motor powering, e.g., a motor driving a hydraulic pump needs to be explosion proof if it is positioned on the mine side of the fresh air side door, i.e. in return air, when in a mine environment possibly containing combustible gases like coal mines which can contain methane, as set forth in mining regulations. Also, the use of multiple pumps increases the cost of the leaf drive system and increases the fire hazard by having more potential ignition sources.
Another problem with the use of multiple door drive systems is the performance of
Kennedy John M.
Kennedy William R.
Gay Jennifer H
Jack Kennedy Metal Products and Buildings Inc.
Neuder William
Senniger Powers Leavitt & Roedel
LandOfFree
Mine door power drive system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mine door power drive system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mine door power drive system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2832359